This is not the reason.
It’s possible that the PWM signal is janky somehow, but I don’t use the standard servo library, the signal is generated by hardware (timer in PWM mode) not software. Hardware interrupts should make no difference, because the PWM timer keeps running even when interrupts occur. Also, my logic analyzer seems to think the signal is very accurate.
That said, this is new code, and there may be that some other piece of code is interfering with how this is supposed to work. Please post your exact config file, I will load it on my board and see what the logic analyzer says.
If nothing else, maybe I can make a mode which only sends servo signals when the output value changes. No signal, no jitter, right?